There are many known casino games using decks of playing cards or other sets of game indicia to determine the outcome of the game. For example, many casino games of chance utilize reels displaying a fixed set of reel symbols which, when obtained in certain predetermined combinations, may trigger an award. These reel games are commonly referred to as reel slot machines or slot machines.
Slot machines can contain any number of reels, although most slot machines contain three, four, or five reels, and any number of pay lines, although most slot machines include one, three, five, eight, or nine pay lines. For example, in some slot machine games, each reel on a slot machine may index at a plurality of positions or stops, each of which contains a symbol or a blank. While the number and location of index positions can vary from game to game, within any particular game, the number and location of index positions are fixed. Slot games are usually differentiated by the award tables and winning symbol combinations, but slot games are otherwise virtually identical to one another.
Purely mechanical slot machines operated by stopping spinning reels with a mechanical brake to determine the outcome of the game. These mechanical machines were limited in two ways. First, the odds of any particular symbol combinations was constrained by the number of reels and the number of symbols per reel. For example, in a slot machine with three reels having ten symbols per reel, the odds of each combination appearing are 1:1,000 (i.e., 10×10×10=1,000). To vary the odds (and thus the payouts that could be issued for the particular combination) the quantity of each type of symbol may differ. For example, a ten symbol reel strip may include five cherries, four grapes, and one lemon. In an example using three such reels, the odds of obtaining three lemons would be 1:1,000, whereas the odds of obtaining three cherries is 125:1,000. In such an example, the greatest payout that could be paid while maintaining a house edge (i.e., a statistical expectation of profit) would be 999 to one for three lemons, thereby guaranteeing that the house wins one coin when a payout is paid for three lemons.
Modern slot machines, whether video or mechanical are controlled via computer and are not so constrained. In Telnaes, U.S. Pat. No. 4,448,419, a fixed digital map is created with all possible symbol combinations within a game mapped to random numbers that may be generated by a random number generator (“RNG”). Telnaes teaches, however, that combinations may be duplicated within the fixed map. Thus, the losing combination of BAR-7-(blank) may be mapped to thousands or tens of thousands or hundreds of thousands of random numbers. Because the likelihood of each combination is not limited by the physical quantity of reel stops (i.e., the quantity of symbols printed on each reel strip) but rather the quantity of random numbers, the manufacturer has total control over the odds of any particular symbol combination occurring. For example, an RNG may be configured to generate one million possible numbers with losing combinations mapped to 999,999 of the possible random numbers and a winning combination mapped to one of the possible random numbers. In such an example, the odds of obtaining a winning combination would be 1:1,000,000 whether each reel strip has one or ten or one hundred reel stops. Using such a fixed map, the display of the reels is merely a way to visually report the outcome of the game, rather than determine the outcome of the game. That is, in such a slot machine, the outcome is determined by the RNG generating a random number and a logic controller using the fixed map to determine the outcome mapped to that random number. The display (whether a computer-generated graphical display or physical reels controlled by stepper motors) is then controlled by the logic controller to display the symbol combination mapped to the random number generated according to the fixed map.
The benefit of using a fixed map is that the virtual reels (as opposed to physical reels) permit payouts that are not constrained by the size (i.e., quantity of reel stops) of the reels. This means that large payouts can be offered by creating a fixed map that has certain outcomes mapped to only a few possible random numbers, independent of the quantity of reels, reel symbols, or reel stops.
Outwardly, a slot game appears to operate as follows: a wager is received to initiate the slot machine. Often, games are structured so that multi-coin wagers are allocated between the number of paylines activated and the number of coins per payline. For example, a 45 coin wager may be allocated with five coins wagered on each of nine paylines.
A “spin” button is actuated on the player interface. Outwardly, actuation of the spin button appears to cause the reels to spin and, upon stopping, determine the symbol combination making up the game outcome. Inwardly, however, actuation of the spin button causes the RNG to randomly select a number. The slot machine's logic controller uses the fixed map to “look up” the outcome mapped to the random number selected. The logic controller then controls the display (again, it is irrelevant whether the slot machine utilizes a video display or mechanical reels) to display the outcome mapped to the random number selected. The logic controller issues a payout, if any, associated with the outcome mapped to the random number selected according to a fixed paytable.
As may be appreciated, the use of mapping has been applied to all modern gaming machines, regardless of how the game is conducted or displayed. That is, whether the game utilizes cards, tiles, numbers, or any other game indicia, mapping is used to translate the output of an RNG into an outcome, which the logic controller can then display visually at a display.